Getting Deep in the Greenhouse World

Getting Deep in the Greenhouse World

Blog entry 02 03 10: Getting Deep in the Greenhouse World

We drilled over a thousand meters (3,300 feet +) of core, reaching deep in the Greenhouse World. One surprise after another was seen in the cores for the past couple of days. The questions, ideas and hypotheses have been multiplying like bubbles in a boiling pot of water. All rising up to the surface, where most will vanish into thin air as new data come in or new ideas rise up to take their place. The co-chiefs have been running around asking questions, probing various scientists for insights and clues on what we have just recovered. While the data are still being processed and will continue to be worked on for the upcoming months and years, this is what I can say: we have blasted deep into the Greenhouse World. Not some upper most section but far into the hothouse world.

We have indeed gone into uncharted places for past climate changes in Antarctica. We were so surprised by what we recovered, it seemed as though we went through a geologic temporal anomoly that hurled us back in time, deep into the Greenhouse World along the Antarctic coast. We are all collecting data and trying to understand how we ended up this far back in time.

Truly, we have gone where no drilling bit has gone before.

The sediments also tell a dramatic story of chaos and massive changes on the margin of this part of Antarctica that occurred during the transition from the extreme warmth into the start of the icehouse world. We are all just shaking our heads in amazement and sighing from the exhilaration that we were able to be part of these discoveries. The story of this part of Antarctica’s margin will also be tied to the studies from a previous Ocean Drilling Program expedition to the South Tasman Rise (STR), which is a small piece of continental block that ripped away from Australia and Antarctica about 30 to 40 million years ago. However, before it did, it was up against Antarctica at about 62 degrees latitude, so the cores taken from there from this time were actually closer to Antarctica than to Australia. However, the spreading of Australia and Antarctica finally resulted in the STR to go with Australia and therefore, this piece of Antarctica is now much farther north.

This is a reconstruction of Antarctica and Australia at 40 million years ago. The white area to the bottom is Antarctica, the small island above it is the South Tasman Rise, which use to be above sea level but now is thousands of feet below sea level; and then Tasmania and Australia to the north.

This is a plate reconstruction at 33.5 million years ago.

What is so special about the cores for this site is that we had generally very good recovery for the lower part of the cores. This included the times during the start of the icehouse world as well as the greenhouse to hothouse worlds. The co-chiefs and the scientists have worked so hard and long during the coring and now we are all working as a community developing ideas on how to best explain what we have now in the refrigerator heading back to the core repository for further examination later in the spring or early summer.

We are now heading for the second site of this expedition: the high resolution Holocene (<10,000 years old). It is in a topographic low on the shelf that was formed when the ice sheets advanced onto the shelf gouging out a deep trough that is over 1,000 meters deep (3,300 feet). Here fine sediments and the shells from one-cell organisms called diatoms that live in the upper part of the ocean and makes its own food like plants can be deposited without being carried away by bottom currents. Shorter cores taken previously in this area see what looks like annual layers. This suggests that we may be able to get an ultra high resolution record of climate change near Antarctica, but in a marine setting. It will be like getting a tree ring or ice core record, but with all of the data that a marine core can provide. It is an extraordinary opportunity for science. We should be there by tomorrow and coring within 12 hours after that. We expect to be able to get a 10- meter core every 30 to 40 minutes. This will definitely tax all of the scientists and techs. But we are all excited by this next potential bonanza for scientific discovery.